1. Field of the Invention
Example embodiments of the present invention relate to a thin-film transistor (TFT) and a method of manufacturing the TFT. More particularly, example embodiments of the present invention relate to a TFT capable of improving electrical characteristics between a channel region and a protective layer to decrease an off current, and a method of manufacturing the TFT.
2. Description of the Related Art
Liquid crystal display (LCD) devices are one of the most widely used types of flat panel display (FPD) devices. An LCD device includes two substrates including electrodes and a liquid crystal layer interposed between the substrates. Liquid crystals of the liquid crystal layer vary arrangement in response to an electric field applied thereto, and thus light transmittance of the liquid crystal layer is changed, thereby displaying an image. Recently, the screen size and the resolution of LCD devices have been increased.
One of the substrates of the LCD device includes a plurality of pixel electrodes arranged in a matrix shape, and another of the substrates of the LCD device includes a common electrode. When a voltage is applied to each of the pixel electrodes, the image is displayed. A thin-film transistor (TFT) that is a switching element having three terminals is electrically connected to each of the pixel electrodes. The TFT including a gate electrode, a source electrode and a drain electrode, a gate line and a data line are formed on the substrate. The gate line transmits a gate signal to control the TFT. The data line transmits a voltage to the pixel electrode. The source electrode is electrically connected to the data line. The drain electrode is spaced apart from the source electrode, and faces the source electrode. The source electrode and the drain electrode are electrically connected to a semiconductor pattern that is under the source and drain electrodes through an ohmic contact layer.
When a gate on voltage Von is applied to the gate electrode, the voltage is applied to the drain electrode through the source electrode and a channel region of the semiconductor pattern. The channel region is exposed between the source and drain electrodes.
However, electrical characteristics of the semiconductor pattern may be poor. Thus, leakage current flows from the channel region when the TFT is turned off. When the off current is increased, contrast ratio is decreased and afterimages are increased. In addition, manufacturing time is increased thereby increasing manufacturing costs for compensating the electrical characteristics of the semiconductor pattern.